1. Field of the Invention
The present invention relates to disk drives for computer systems. More particularly, the present invention relates to a disk drive for updating operating zone parameters with adapted zone parameters calibrated in the field.
2. Description of the Prior Art
The zone parameters of a disk drive are typically calibrated during manufacturing and stored in a reserved track on the disk. During spin up, the calibrated parameters are read from the reserved track, stored in volatile semiconductor memory, and used to program the disk drive relative to the radial position of head during read and write operations. The prior art has suggested to recalibrate the zone parameters periodically throughout the life of the disk drive to compensate for changes that occur over time. However, the prior art""s approach of recalibrating all of the zone parameters on a periodic interval may not result in optimal performance.
There is, therefore, the need for a disk drive employing an improved algorithm for recalibrating the zone parameters in the field to compensate for changes that occur over time due, for example, to changes in environmental conditions.
The present invention may be regarded as a disk drive comprising a disk comprising a plurality of tracks, each track comprising a plurality of data sectors, the tracks banded together to form a plurality of zones. The disk drive further comprises a head actuated radially over the disk for writing data to and reading data from the data sectors, and a buffer for storing operating zone parameters and adapted zone parameters for each of the plurality of zones. The disk drive further comprises an adapted zone parameter counter, and a disk controller for operating in a plurality of states including an active state and an off-line state. During the off-line state, the disk controller calibrates at least one of the adapted zone parameters. During the active state, the disk controller receives a read command from a host computer to read data from at least one of the data sectors. The disk controller seeks the head to a selected one of the zones comprising the data sector corresponding to the read command, programs the disk drive with the operating zone parameters corresponding to the selected zone, and reads data from the data sector. If a read error associated with reading data from the data sector is detected, the disk controller performs a data-recovery firmware procedure using the adapted zone parameters to recover the data from the data sector. If the data is successfully recovered from the data sector using the data-recovery firmware procedure, the disk controller increments the adapted zone parameter counter and updates the operating zone parameters with the adapted zone parameters if the adapted zone parameter counter exceeds a predetermined threshold.
In one embodiment if the adapted zone parameter counter does not exceed the predetermined threshold after a predetermined number of attempts to recover data using the data-recovery firmware procedure, the adapted zone parameter counter is reset. In another embodiment, the updated operating zone parameters are written to the disk. In yet another embodiment, the disk drive employs an on-the-fly error correction code (ECC), and the read error is detected when the ECC indicates a data sector is unrecoverable on-the-fly.
The present invention may also be regarded as a method of calibrating a zone parameter of a disk drive in the field, the disk drive comprising a disk comprising a plurality of tracks, each track comprising a plurality of data sectors, the tracks banded together to form a plurality of zones. The method comprises the steps of actuating a head radially over the disk for writing data to and reading data from the data sectors, and storing operating zone parameters and adapted zone parameters in a buffer for each of the plurality of zones. During an off-line state of the disk drive, at least one of the adapted zone parameters is calibrated. During an active state of the disk drive, the head is positioned over a selected one of the zones comprising a data sector corresponding to a read command. The disk drive is programmed with the operating zone parameters corresponding to the selected zone. Data is read from the data sector, and if a read error is detected associated with reading data from the data sector, a data-recovery firmware procedure is executed using the adapted zone parameters to recover the data from the data sector. If the data is successfully recovered from the data sector using the data-recovery firmware procedure, an adapted zone parameter counter is incremented and the operating zone parameters are updated with the adapted zone parameters if the adapted zone parameter counter exceeds a predetermined threshold.